Integrated modelling to assess long-term water supply capacity of a meso-scale Mediterranean catchment Lila Collet a, ⁎, Denis Ruelland b , Valérie Borrell-Estupina a , Alain Dezetter c , Eric Servat c a UM2 — UMR HydroSciences Montpellier, Place E. Bataillon, 34395 Montpellier Cedex 5, France b CNRS — UMR HydroSciences Montpellier, Place E. Bataillon, 34395 Montpellier Cedex 5, France c IRD — UMR HydroSciences Montpellier, Place E. Bataillon, 34395 Montpellier Cedex 5, France HIGHLIGHTS • A model integrating water resources and demands is proposed on a meso-scale basin. • An indicator that complies with stakeholder's needs assesses water supply capacity. • Climate change impacted water resources availability and agricultural water demand. • Anthropogenic changes have led to an increase in domestic water demand. • Water supply capacity has worsened over the last 50years notably downstream. abstract article info Article history: Received 29 March 2013 Received in revised form 13 May 2013 Accepted 14 May 2013 Available online xxxx Editor: Damia Barcelo Keywords: Climate variability Integrated modelling River Hérault Water demand Water resources Water supply assessment Assessing water supply capacity is crucial to meet stakeholders' needs, notably in the Mediterranean region. This region has been identified as a climate change hot spot, and as a region where water demand is contin- uously increasing due to population growth and the expansion of irrigated areas. The Hérault River catch- ment (2500 km 2 , France) is a typical example and a negative trend in discharge has been observed since the 1960s. In this context, local stakeholders need first to understand the processes controlling the evolution of water resources and demands in the past to latter evaluate future water supply capacity and anticipate the tensions users could be confronted to in the future. A modelling framework is proposed at a 10-day time step to assess whether water resources have been able to meet water demands over the last 50 years. Water sup- ply was evaluated using hydrological modelling and a dam management model. Water demand dynamics were estimated for the domestic and agricultural sectors. A water supply capacity index is computed to assess the extent and the frequency to which water demand has been satisfied at the sub-basin scale. Simulated runoff dynamics were in good agreement with observations over the calibration and validation periods. Do- mestic water demand has increased considerably since the 1980s and is characterized by a seasonal peak in summer. Agricultural demand has increased in the downstream sub-basins and decreased upstream where irrigated areas have decreased. As a result, although most water demands were satisfied between 1961 and 1980, irrigation requirements in summer have sometimes not been satisfied since the 1980s. This work is the first step toward evaluating possible future changes in water allocation capacity in the catchment, using future climate change, dam management and water use scenarios. © 2013 Elsevier B.V. All rights reserved. 1. Introduction In the context of climate change and population growth, the ability of water resources to satisfy different demands is essential (Vörösmarty et al., 2000), particularly in Mediterranean regions where difficulties in meeting water needs have already resulted in increasing social tensions (Margat and Treyer, 2004). The Mediterranean region has been identi- fied as a climate change hot-spot (Giorgi, 2006), and as a region where population growth is strong (+30% over the last 20 years) (Abis, 2006). As a result, mean water resources around the Mediterranean basin could decrease between 30% and 50% by 2050, leading to increas- ing water stress (Milano et al., 2012, 2013a). The worrying situation in this region highlights the need to devel- op methodological approaches to face such issues. Integrated studies, which investigate changes in water availability and water demand Science of the Total Environment 461–462 (2013) 528–540 Abbreviations: AWD, Agricultural Water Demand; DWD, Domestic Water Demand; F agg , Aggregation Function; NSE, Nash–Sutcliffe efficiency criteria; NSE lf , Nash–Sutcliffe efficiency criteria during low-flows; VE, Volume Error; VE m , mean Volume Error; WD, Water Demand; WRA, Water Resources Availability; WSCI, Water Supply Capacity Index. ⁎ Corresponding author. Tel.: +33 4 67 14 90 36. E-mail address: lila.collet@um2.fr (L. Collet). 0048-9697/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.scitotenv.2013.05.036 Contents lists available at SciVerse ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv